Michael White is caught off guard by the resignation of Sir Ming Campbell at the end of a lively Commons day.

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Breakfast, west London

To add to Gordon Brown's political woes, both sides in the abortion war are itching to reopen hostilities this winter, though this morning's debate on Today's top 8.10am spot between David Steel and Professor Stuart Campbell was rare for being civil and outrage-free.

Encouraged by 4D photos of unborn babies - a technique pioneered by Prof Campbell, an obstetrician - the anti-abortion lobby wants to restrict the upper legal limit (now 24 weeks) to 22, 20 or even 18 on the grounds that foetal viability is earlier than it was when Lord Steel's 1967 Abortion Act was passed.

For many of them, however, this is what leftwingers might call a transitional demand - on the road to the nirvana of no abortions at all in a world where all babies are loved and cared for.

Our debate lacks the "culture wars" absolutism of America's, but it is intensifying. Those 4D pix are hard to ignore. No one here has yet been murdered to uphold the sanctity of human life.

On the other side, libertarian MPs like Evan Harris, the Lib Dem doctor who sits for liberal Oxford West and Abingdon, see the upcoming human tissue and embryos bill as a vehicle to liberalise the law in ways that would allow non-doctors to supervise abortion which technology - the driving force for both sides - now makes easier.

As with the 1990 legislation to regulate embryo research, the new bill has nothing to do with abortion as such, but it is sufficiently close to permit amendments in this field. Then a rapid consensus restricted abortion to 24 weeks instead of 28. MPs voted on all options from 26 to 18 weeks.

Governments get jittery because this is a faith issue, especially for Catholics and Muslims, though many other denominations share the hostility to the scale of abortion in Britain - around 200,000 a year now take place.

There are currently only a handful of Muslim MPs and peers; around 66 Catholic MPs - as different as Ruth Kelly, Ann Widdecombe, George Galloway and (yes, I know what you're thinking) Gerry Adams. But there are many more Catholic voters who swing heartland Labour seats in Scotland and north-west England.

Expect a Brown government to wriggle. Abortion is big in Scotland, one reason why it remains a power reserved to Westminster under devolution laws. It makes David Steel's decision to promote the 1967 reform as a new boy MP - just 29 - all the more impressive. Like GB, he is a son of the manse, born in Kirkcaldy - as GB was not.

So his civil exchange with Prof Campbell was a good sign. His mind is open to change, Lord Steel declared. But he kept asking the professor to explain why the British Medical Association voted this summer for the status quo - which he will endorse unless persuaded otherwise.

Prof Campbell, who has done many abortions and does not sound fundamentalist either, is now an 18-weeks man. He explains that he always stops a baby's heart before expelling it from the uterus. The details never sound reassuring. Odd though, I thought I heard him admit that many of these babies (born on the 20-24 week viability margin) are handicapped.

Norman Baker, the tireless Lib Dem MP for Lewes, is reopening doubts about the circumstances of David Kelly's death. There were no fingerprints on the knife blade he allegedly used to kill himself, an odd way to do it too, the MP is saying, on the strength of FoI applications.

I admire Mr Baker, who sometimes seems to undervalue his own usefulness as a Trouble Maker. There are always some, rarely enough, in parliament. By the nature of their work they are often argumentative loners. As investigative reporters manque, they are also drawn to conspiracy theory which is always fun, but more often wrong than right.

I was first asked who murdered the weapons scientist by Arabic TV on the day his body was found. No one, I replied. That remains my view on the evidence, though Mr Baker raises an interesting point.

Dr Kelly sounds like a loner, who didn't discuss his post-Gilligan problems - caught between the BBC and the government - even with his wife until they both heard him being discussed as the then-unnamed source on Channel 4 News. His mother appears to have killed herself in his teens, the Hutton inquiry was told. That must have been a dreadful burden to carry.

So MPs and peers may have to move out of the Houses of Parliament for up to three years to allow essential repair of this great, mid-Victorian masterpiece to be completed in less than 30 years. That's what newspapers report today.

I'll believe that when it happens. They moved for part of the war after Hitler's Luftwaffe destroyed the Commons chamber one night in May 1941 - part of the time to Church House across Parliament Square. There is a plaque on a wall there to commemorate it.

But that was sheer necessity. As with schools and hospitals, parliament has recently spent a lot on itself repairing decades of poverty and neglect and giving backbenchers better facilities to cope with the modern deluge of constituency business. I doubt that MPs and peers will want to decant.

So today's reports may simply be an opening bid by officialdom to persuade them to accept some lesser evil. But never underestimate the power of officials here, MPs and peers constantly remind me. Meanwhile repairs to the press gallery are almost finished. We return from our own exile today.

Mid-afternoon,Westminster: If there is anything funnier than the sight or sound of Labour politicians plotting against the leadership it is Lib Dems scurrying through the undergrowth in similar pursuit.

The murmurings against Sir Ming as polls erode the party's cherished position are real. Late in the day they have noticed that he was too old to succeed Charles Kennedy in 2006 - something that was pretty obvious at the time.

But Ming's loyal deputy, Vince Cable, the wise Obi-Wan Kenobi of the Lib Dem galaxy, was surely right when he said on today's World at One that it would be ''absolutely foolish to rush into a decision'' when public opinion is so volatile. He had the wit to admit Ming's job is ''certainly under discussion. I don't think it's under threat."

Barely a fortnight ago GB was as unbeatable as the Wallabies and it was David Cameron supposedly heading for an early bath. Sir Ming is a victim of circumstances beyond his control - a Tory revival under a liberal-sounding leader. It shocks them. It shouldn't.

At least no one can accuse level-headed Dr Vince of wanting the job. Though two years younger at 64 the salsa dancing, economist MP for Twickenham looks even older than his leader, though he is very sharp. Ming's remaining task is to keep the seat warm for N**k C***g, not exactly top secret info. The Twickenham Strangler was characteristically discreet on that point.

Most wannabe plotters have stayed undercover, as they did last time. So the airwaves are left to the amateurs or retired Lib Dem colonels like Lord Bill Rodgers (last month) and today by Lord Dick Taverne, an ex-Labour defector ousted as an MP by Labour's Margaret Jackson at Lincoln in 1974. She also acquired a husband there, Leo Beckett. Taverne's clever. He knows it, but is his finger on any pulse but his own?

On air was also a chap called Sir Chris Clarke, a former party leader on the admirable Local Government Association, whom the BBC passed off as a senior Lib Dem. Enjoying his 15 seconds, Sir Chris told Ming to go with dignity - if you can tell someone that on the World at One - and go back to being foreign affairs spokesman, where ''the world listens to you.'' Hmmm...

I sometimes feel strong enough to read Daily Mail editorials after a light lunch. After reading today's no one can say Gordon Brown wasted all those hours in a rant-fest with the paper's editor-in-chief, Paul Dacre.

How dare those failed ''political pygmies with their pathetic records'' raise a hand against the man who delivered the ''one resounding success of the Blair decade.'' Yes, the economy, silly, not the rugby world cup. So goes today's rant against the Byers, Milburn, Falconer clique. I intend to cut it out and keep it.

Footnote: I am advised that Professor Stuart Campbell regards an 18-week upper limit for abortions as a transitional position and that a ''civilised and humane society'' will eventually settle for 12 weeks, as an article for the BBC website Campbell appears to suggest.

8pm, Westminster

No, you're right. I didn't believe Ming would go until someone (not the BBC's Nick Robinson) persuaded me that Chris Huhne was threatening to challenge him for the leadership if he didn't. It wasn't dignified, but it wasn't messy either.

If true, Huhne will be judged the regicide, as Michael Heseltine was for the Tories in 1990, and pay a price when activists vote for Ming's successor. The bookies assume it will be Nick Clegg. For once I think they're right. Whoever wins it will make David Cameron the longest serving major party leader, having been in post since December 2005. Wow!

By coincidence, as I was being persuaded that dusk was falling on Ming I was watching it fall on the Guardian's little office at Westminster - for the first time in 20 years. Let me explain.

For the whole of that period we have had a room under Big Ben with a light well, but no light - and no window. It has been impossible to tell if it was blazing June outside or a snowstorm in February.

The parliamentary authorities have just upgraded our office space to meet modern health and safety standards. It is always a mixed blessing, but they have been kind: we have been granted two small windows suitable to a grade one listed palace. We can see daylight at last - and last night we saw dusk fall on us - and on Ming.